As a technique for improving system throughputs in an environment where numerous terminals exist, the technique of full-duplex communications has been investigated. In full-duplex communications, one terminal simultaneously carries out transmission and reception using the same frequency, so that it is possible to increase the efficiency of utilization of time resources when compared with conventional half-duplex communications. Specifically, increase in the throughput can be expected by up to double.
A problem associated with full-duplex communications is that a signal to be transmitted may enter the receiver's side in a roundabout manner via a certain path in the terminal itself that transmits the signal, causing self-interference with respect to a signal to be received. In general, a signal to be transmitted is transmitted at a large level relative to that of a signal to be received which is received in an attenuated state. As a result, the self-interference level due to introduction of unwanted signal is relatively large when compared with the level of the signal to be received. As a result, the signal to be received is likely not received correctly due to the self-interference acting as the factor. Here, receiving correctly a signal in this context means, for example, that a signal is received with a reception quality (signal-to-interference-plus-noise ratio (SINR), etc.) ensuring that the signal can be received at or below a certain frame error rate.
Also, in realizing full duplex communications, not only self-interference but also inter-terminal interference can be a problem. Inter-terminal interference refers to interference given by a signal transmitted from a terminal that performs uplink transmission to a terminal that performs downlink reception.
The above-mentioned self-interference and inter-terminal interference cause decrease in the throughput of the system in realizing the full duplex communications.